Want to build your own completely customized, artistic, totally non-toxic house with a material that’s literally dirt cheap? Roll up your sleeves and dive into this primer on cob, an earthen mixture that is used to build fireproof, earthquake-resistant, natural structures from homes to pizza ovens. Here you’ll learn about the history of cob, see how it’s made and get inspired by images of the many gorgeous cob structures that have been built around the world.

What is Cob?

Cob is a mixture of clay, sand and straw that can be worked like clay and sculpted into free-form structures including houses, commercial buildings, garden walls, benches, ovens and more. In use for thousands of years, cob is among the easiest natural building materials to work with because there’s no need to form it into bricks or to fire it.

Not only is cob fireproof, it’s also earthquake resistant. It’s breathable, so it allows the exchange of air between indoors and out. Because cob walls are generally about two feet thick, it makes for excellent thermal mass. This means that cob can be used to create passive solar houses that absorb heat during the day and release it at night, reducing or even eliminating the need for heating and cooling in some climates.

Many of the characteristic homes of the United Kingdom, with whitewashed rounded exterior walls and thatch roofs, are made of cob. Some that still stand today were built as long as 500 years ago. Many of the oldest man-made structures in Afghanistan are also made of cob. Renewed interest in traditional, natural building techniques have led to a revival of cob construction around the world.

Incredibly inexpensive compared to modern building materials, cob is also among the greenest choices, especially when the earth used to create it can be sourced from the building site. Cob requires no finishing other than a layer of earth plaster. Not only does cob provide an earthy, welcoming warmth, it also eliminates the need for potentially toxic building materials like insulation and drywall.